Colorado’s law “gravely menace[s]…[t]he health, comfort and prosperity of the people” of neighboring states,” the former administrators write in their brief.

“The federal government made the choice in 1970 that a uniform, comprehensive, and consistent national approach to controlled substances was necessary,” the brief continues. “Principles of federalism, properly understood, therefore support the plaintiff States’ suit against Colorado.”

Under the Obama administration, the Justice Department has declined to enforce federal laws on marijuana in states that have legalized it for recreational use.

The brief, filed on their behalf by the law firm Gibson, Dunn & Crutcher, is the first time all nine former DEA administrators have joined together on a signed statement.